1. Field of the Invention
The present invention relates to a semiconductor memory device and, more particularly, to a voltage generation circuit, which can generate voltages of two levels that are higher than a power supply voltage, and a semiconductor memory device including the same.
2. Description of the Related Art
A conventional semiconductor memory device makes use of a voltage level higher than a power supply voltage to drive a word line and makes use of a precharge voltage equal to or half of the power supply voltage to precharge a bit line. For this reason, the semiconductor memory device includes a high voltage generator to generate the high voltage and a precharge voltage generator to generate the precharge voltage.
The inclusion of both these voltage generators is because the power supply voltage of the conventional semiconductor memory device is high. As the voltage level of the power supply of the semiconductor memory device is reduced to 1.2 V or less, the precharge voltage for precharging the bit line should be lower than the voltage applied to the word line and higher than the power supply voltage. Accordingly, a precharge voltage that is different from that of the conventional semiconductor memory device from the precharge voltage is needed.
When the precharge voltage is equal to or half of the power supply voltage, the precharge voltage generator is configured without a capacitor. However, when the precharge voltage is higher than the power supply voltage, the precharge voltage generator typically includes a capacitor to pump the power supply voltage.
Therefore, a semiconductor memory device using a low power supply voltage has an increased layout area compared to a semiconductor memory device using a high power supply voltage, because both a high voltage generator and a precharge voltage generator include capacitors.